Short answer
As a general rule, avoid digital keystone correction whenever possible—it should be viewed as a last resort, not a primary setup tool.
[Keystone Applied]
+-------------------+ <-- Projected Image Area
| /-------------/ | <-- Scaled Active Picture (Loss of Resolution)
| / Active / |
|/ Picture / | <-- Unused, glowing grey border
+-------------------+
How Keystone Correction Degrades the Image
When a projector is angled upward or sideways relative to the screen, the image distorts into a trapezoid (the "keystone" effect). Digital Keystone Correction corrects this by reshaping the frame electronically using internal image processing software.
Resolution Compression: Digital keystone scales down the original signal to fit within a distorted pixel grid, turning off unused pixels around the border. This reduces overall image resolution and sharpness.
Light Leak / Grey Borders: The unused pixels on the micro-chip do not stop casting light; they emit an annoying trapezoidal grey halo or border around your screen.
Increased Input Lag: The real-time image scaling adds processing overhead, significantly degrading gaming performance.
Preferred Alternatives
Optical Lens Shift: Moves the physical lens housing vertically or horizontally without tilting the projector, preserving 100% of native resolution and light output.
Physical Alignment: Adjust the height and placement of the mount or stand so the projector lens aligns perpendicularly with the screen center.